ICIs target key regulatory pathways including programmed cell death protein 1 (PD-1), its ligands PD-L1 and PD-L2, and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), thereby enhancing CD8+ T-cell-mediated cytotoxicity against tumor cells [10]. The gene discussed is PDCD1; the disease is neoplasm.